My husband sold a canoe to a guy, and felt prompted to witness to him. Turned out the man was a rabid atheist and an atheist evangelist.
He demanded my husband's email, and started sending him all this atheist propaganda and trying to prove the bible was wrong and there was no God. It was a little over my husband's head, so he asked me to help.
I easily answered all his objections because I have heard them all before! He was preaching a very old atheist religion. So he would get madder and madder with every email, and started attacking me personally, (kind of like CC, but a bit worse! LOL)
His heart was so cold, and I simply could not feel God leading me to waste time debunking all his stupid arguments. So I just didn't reply. Kind of like the ignore button. (See, I have learned so much here!)
He wrote back a few more times, demanding I answer his 5 or so questions which would disprove Jesus forever. I had ignored those questions, they were so transparent and facile. But he kept demanding. Until he realized I was not going to answer his rhetoric anymore.
So definitely a religion. They all read the same books, come up with the same lines, and try to wear you down with nonsense. And no apparent signs that atheism is transforming them into better people. I think that was my last point, that God has changed me in ways I could not change myself. Too subjective for him, of course. But who knows, maybe I planted the seeds that God needed in that person's life, and I won't know till eternity how it comes out.